烧瓶/WTF 表单将变量传递给模板给出 500 错误，表单未定义

Question

我一直在尝试将 WTForms 表单中的变量传递到模板中，但它给我带来了 500 个错误。我基本上是在尝试在结果页面上显示来自上一个表单的用户输入。

但是，我找到的所有解决方案都说我需要声明表单=表单，但是我已经这样做了。这是结果.html给出了错误，但我不确定为什么没有定义表单。

UndefinedError: 'form' is undefined

-bot.py

from flask import Flask, render_template, flash, redirect, url_for
from config import Config
from forms import LoginForm
from flask_bootstrap import Bootstrap
from tweetscript import get_tweets
app = Flask(__name__)
app.config.from_object(Config)
bootstrap = Bootstrap(app)
@app.route('/', methods=['GET', 'POST'])
def login():
form = LoginForm()
if form.validate_on_submit():
flash('Twitter name submitted {}'.format(form.username.data))
return redirect(url_for('results'))
return render_template('login.html', title='Home', form=form)
@app.route("/results")
def results():
return render_template('results.html', title='Results')

if __name__ == "__main__":
app.debug = True
app.run(host='0.0.0.0')

-结果.html

{% extends 'index.html' %}
{% block content %}
<h1> results page, {{ form.username.data }}
</h1>
{% endblock %}

-追踪

Traceback (most recent call last):
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask/app.py", line 2292, in wsgi_app
response = self.full_dispatch_request()
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask/app.py", line 1815, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask/app.py", line 1718, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask/app.py", line 1813, in full_dispatch_request
rv = self.dispatch_request()
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask/app.py", line 1799, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "./bot.py", line 21, in results
return render_template('results.html', title='Results')
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask/templating.py", line 135, in render_template
context, ctx.app)
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask/templating.py", line 117, in _render
rv = template.render(context)
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/jinja2/environment.py", line 1008, in render
return self.environment.handle_exception(exc_info, True)
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/jinja2/environment.py", line 780, in handle_exception
reraise(exc_type, exc_value, tb)
File "/home/pi/bot/project/templates/results.html", line 1, in top-level template code
{% extends 'index.html' %}
File "/home/pi/bot/project/templates/index.html", line 1, in top-level template code
{% extends "base.html" %}
File "/home/pi/bot/project/templates/base.html", line 40, in top-level template code
{% for message in messages %}
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask_bootstrap/templates/bootstrap/base.html", line 1, in top-level template code
{% block doc -%}
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask_bootstrap/templates/bootstrap/base.html", line 4, in block "doc"
{%- block html %}
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask_bootstrap/templates/bootstrap/base.html", line 20, in block "html"
{% block body -%}
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/flask_bootstrap/templates/bootstrap/base.html", line 23, in block "body"
{% block content -%}
File "/home/pi/bot/project/templates/results.html", line 6, in block "content"
{{ form.username.data }}
File "/home/pi/bot/project/venv/local/lib/python2.7/site-packages/jinja2/environment.py", line 430, in getattr
return getattr(obj, attribute)
UndefinedError: 'form' is undefined

Answer 1

错误来自以下事实：您的results函数只返回两件事：页面结果.html及其标题; 但是在您的页面结果中.html您尝试恢复函数中未定义但来自另一个函数(登录)的数据。

一种可能的解决方案是：

...
@app.route('/', methods=['GET', 'POST'])
def login():
form = LoginForm()
if form.validate_on_submit():
flash('Twitter name submitted {}'.format(form.username.data))
return redirect(url_for('results', result_data = form.username.data))
return render_template('login.html', title='Home', form=form)
@app.route("/results/<result_data>")
def results(result_data=None):
return render_template('results.html', title='Results', result=result_data)
...

在您的结果.html页面中：

{% extends 'index.html' %}
{% block content %}
<h1> results page, {{ result }} </h1>
{% endblock %}